By Ambassador Kamala Shirin Lakhdhir

Last month, Southeast Asia's leaders – including Prime Minister Muhyiddin – issued a strong statement at the ASEAN Summit, agreeing that South China Sea disputes must be resolved in line with international law, including the United Nations Convention on the Law of the Sea (UNCLOS).

That message was timely, given the July 12 anniversary of the 2016 ruling by the South China Sea Arbitral Tribunal, which rejected the People's Republic of China's over-reaching maritime claims in waters under the Philippines' jurisdiction as being unfounded under international law.

The ASEAN statement stands as a rebuke of Beijing's bolstering of its military bases through destructive land reclamation and construction in the contested Spratlys with new aircraft deployments and so-called "research stations."

The United States applauds the unity of purpose and the clear impact that ASEAN member nations can have in preserving regional and international freedom of movement.

As U.S. Secretary of State Mike Pompeo stated on July 13, "Beijing's claims to offshore resources across most of the South China Sea are completely unlawful, as is its campaign of bullying to control them."

The Secretary added that in the South China Sea "we seek to preserve peace and stability, uphold freedom of the seas in a manner consistent with international law, maintain the unimpeded flow of commerce, and oppose any attempt to use coercion or force to settle disputes."

The PRC's expansive maritime claims in the South China Sea lack a legal basis in international law. This includes the PRC's maritime claims "based on Nanhai Zhudao" and its claim to "historic rights in the South China Sea", as well as its insistence that James Shoal is the southernmost tip of China.

James Shoal is fewer than 50 miles from Malaysia, and 70 feet underwater. Beijing's claim to James Shoal seems to derive from an old British atlas and a translation error suggesting the underwater shoal was actually a sandbank above the waves.

It isn't, and that sparks several questions: What is the PRC's objective in asserting an unlawful territorial claim so close to Malaysia? Why does the PRC make these specious claims, contort facts, and flout established principles of international law?

The ruling by the Arbitral Tribunal is clear, final, and legally binding on China and the Philippines in addressing their maritime dispute. Yet Beijing has chosen to ignore the decision, and indeed has warned that anyone failing to accept its claims in the South China Sea is doomed to fail.

Earlier this year, the PRC declared a new maritime law enforcement campaign called "Blue Sea 2020." China's announced purpose was to "enhance marine environmental protection," but its real purpose seems to focus on bolstering China's military bases in the contested Spratlys with new aircraft deployments, expanding "research stations," and intimidating other nations' offshore oil and gas exploration.

Access to the South China Sea is essential to the economic prosperity and security of Southeast Asian nations, the lifeblood of their coastal communities and the livelihood of millions of their citizens. The harassment of ships at sea inhibits Southeast Asian nations from accessing the resources off their coasts, as was the case when the West Capella – a drillship hired by Petronas – was tailed by China's government-owned research vessel Haiyang Dizhi 8 and armed Chinese coast guard and maritime militia vessels.

The United States supports the free and open, rules-based order that upholds the sovereign rights and interests of all states regardless of size, power, and military capabilities. All nations that share this vision should not only be alarmed at what is happening, but also be vocal and visible in their cohesive and collaborative response.

In 2010, Beijing's top diplomat famously told Southeast Asian counterparts: "China is a big country and other countries are small countries, and that's just a fact." Over the past 10 years, this has been Beijing's mindset toward the South China Sea.

Under international law, Beijing's maritime claims in the South China Sea are simply not credible. Recent actions by one nation should not compromise the sovereign rights of other nations.

(Kamala Shirin Lakhdhir is the United States Ambassador to Malaysia.)